The present invention concerns an improvement in sintered self lubricating bearings.
As known, the usual method of dimensioning of sintered self lubricating bearings is based upon the maximum admissible value of the product p.multidot.v wherein p is the acting pressure, as defined by the ratio between the load and the surface projected by the bush (inner diameter.times.length), and v is the peripheral velocity of the shaft.
The existence of a maximum value of such product p.multidot.v is a direct consequence of the existence of a surface porosity, in the inner wall of the bearings, which does not allow the build-up of a continuous film of lubricant in many cases wherein the average pressures exceed determined limit values. In cases of this kind, in fact, the lubricant interposed between the bush and the shaft is pushed towards the bush itself, tends to flow into the pores and therefore is "lost" for the purpose of its sustaining capacity.
On the other hand, the porosity of the bearings is an essential functional character of them, because it allows both the soakage "for life" and the circulation of oil through the walls according to the sense imposed by the pressure differences which are established when functioning.